why are you post to eat protein after working out?

So lately I've been reading that people like to eat protein after a work out and I was wonder why ? Should I be eating protein after a work out also I'm Not really trying to lose weight maybe like 5 pounds I just want my body to be toned

Edited Jul 03 2013 09:38 by coach_k
Reason: Moved to the Fitness Forum as more appropriate

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